It was a tale of two weddings continents apart, but there was to be only one happy ending.

In Argentina, Jose Maria Di Bello and Alex Freyre made history as the first same-sex couple to marry in Latin America. Thousands of miles away, Tiwonge Chimbalanga and Steven Monjeza became the first gay men to tie the knot in Malawi.

The different reactions to the two ceremonies, however, suggested that while gay rights in Latin America are advancing, in Africa they are going into reverse.

Although Di Bello and Freyre had to rely on subterfuge, a progressive provincial governor and a 1,500-mile trip to the continent's southern tip, their union was greeted as a breakthrough. Chimbalanga and Monjeza, however, were swiftly arrested and charged with gross public indecency. Campaigners warned that the move indicated a conservative backlash against homosexuality across Africa.

The couple took part in a symbolic, traditional ceremony on Saturday. They were watched by hundreds of onlookers in the conservative southern African state, where homosexuality is illegal and carries a maximum prison sentence of 14 years.

"We met at church where we both pray and we have been together for the last five months," Monjeza told Malawi's Nation newspaper.

The two men are due to appear in court tomorrow. Dave Chingwalu, a police spokesman, told the Reuters news agency they were likely to face further charges and would be held in separate cells.

Marlow Valentine, community engagement and empowerment manager of the Triangle Project in South Africa, said: "We are disgusted and outraged that this couple has been arrested and we call for their release. It is an infringement of their human rights." He said a hardening of attitudes towards gay rights across Africa was being encouraged by US-based Christian evangelical groups.

Uganda's parliament is debating legislation that will allow homosexuality to be punishable by death. Sudan and northern states in Nigeria can already enforce the death penalty. Burundi criminalised homosexuality this year, joining 37 African countries where gay sex is outlawed.

"We are certainly going backwards in terms of legislation," Valentine said. "South Africa is the only country in Africa that constitutionally protects the rights of gay people, but it has been very quiet about other countries here becoming more conservative."

Daniel Molokele, a human rights lawyer based in South Africa, said: "It's very disappointing news and continues to take Africa backwards. Countries like Malawi and Uganda should be following the trend set by South Africa and adapting its constitution in a progressive way."

In Latin America policies and attitudes have mellowed over the past two decades and in most countries it is now illegal to discriminate on the basis of sexual orientation. Buenos Aires, Bogota and Mexico City boast gay pride parades and gay-friendly districts where same-sex couples can kiss and hold hands in public.

Yesterday Di Bello, 41, and Freyre, 39, became the continent's first gay married couple. The pair sidestepped a court ruling blocking their wedding in Buenos Aires by holding the ceremony in Ushuaia, capital of Tierra del Fuego province and the world's southernmost city.

They exchanged rings at a civil ceremony witnessed by state and federal officials, prompting jubilation by gay rights activists and consternation from the Catholic church.

"My knees didn't stop shaking," said Di Bello. "We are the first gay couple in Latin America to marry." The couple, both Aids activists who have HIV, wore sports coats and red ribbons.

Argentina's constitution does not specify whether marriage must be between a man and a woman, in effect letting provincial and city officials interpret the law.

After officials in Buenos Aires balked at the last minute, Di Bello registered as a resident of Tierra del Fuego, hoping the governor, Fabiana Rios, a champion of gay rights, would back the wedding. The registration and ceremony were kept secret to avert legal challenges.

The governor said the marriage was "an important advance in human rights and social inclusion and we are very happy that this has happened in our state".

Same-sex civil unions have been legalised in Uruguay and parts of Argentina, Brazil and Mexico but same-sex marriage, which confers extra rights including adoption, was banned. Mexico City legalised same-sex marriage last week.